Make init function UNSAFE

src/main/java/net/minestom/server/entity/Player.java

@@ -229,10 +229,11 @@ public class Player extends LivingEntity implements CommandSender {
      * Init the player and spawn him.
      * <p>
      * WARNING: executed in the main update thread
+     * UNSAFE: Only meant to be used when a netty player connects through the server.
      *
      * @param spawnInstance the player spawn instance (defined in {@link PlayerLoginEvent})
      */
-    public void init(@NotNull Instance spawnInstance) {
+    public void UNSAFE_init(@NotNull Instance spawnInstance) {
         this.dimensionType = spawnInstance.getDimensionType();
 
         JoinGamePacket joinGamePacket = new JoinGamePacket();

src/main/java/net/minestom/server/network/ConnectionManager.java

@@ -503,7 +503,7 @@ public final class ConnectionManager {
 
             Check.notNull(spawningInstance, "You need to specify a spawning instance in the PlayerLoginEvent");
 
-            waitingPlayer.init(spawningInstance);
+            waitingPlayer.UNSAFE_init(spawningInstance);
 
             // Spawn the player at Player#getRespawnPoint during the next instance tick
             spawningInstance.scheduleNextTick(waitingPlayer::setInstance);